How to Hide Mplus Intercom Subscription Admin Menus

function plt_hide_mplus_intercom_subscription_menus() {
	//Hide the "Intercom Subscription" menu.
	remove_menu_page('mplusis-settings');
	//Hide the "Intercom Subscription → Intercom Subscription" menu.
	remove_submenu_page('mplusis-settings', 'mplusis-settings');
	//Hide the "Intercom Subscription → License Activation" menu.
	remove_submenu_page('mplusis-settings', 'mplusis-license-activation');
}

add_action('admin_menu', 'plt_hide_mplus_intercom_subscription_menus', 11);

Where do I put this code?